Thick hyperviscous mucus and delayed mucociliary clearance are important elements underlying cystic fibrosis (CF) pathogenesis, but currently available therapeutics exhibit limited efficacy to combat mucus stasis. In addition, biofilms that populate the CF lung contribute to reduced lung function and are typically not affected by current mucolytics and severely limit antimicrobial efficacy. Novel mucolytic therapies that innately reduce the viscosity of CF sputum, reduce the viability, cohesion and viscosity of pathogenic biofilms and improve mucociliary clearance would provide an important therapeutic advance to combat respiratory decline. Our preliminary data demonstrate that PAAG, a soluble, nontoxic polycationic polysaccharide, has robust effects on CF sputum and reduces the viscosity and cohesion of biofilms grown from CF isolates. This reduction in biofilm cohesion is anticipated to enhance activity of standard antibiotics. Based on this, we hypothesize that PAAG could be an effective pulmonary mucolytic for CF patients that will improve airway clearance and improve antibiotic activity, but requires further studies to understand its pharmacology, formulation, and breadth of effects to propose development as a human therapeutic. Demonstration of PAAG's activity will provide crucial proof of concept data and provide a scientific basis for testing its activity in human subjects. In this project, we will assess PAAG's role in reducing the viscosity of patient derived sputum using state-of-the-art rheometry. Further we will demonstrate that the reduction in viscosity improves mucociliary clearance by assessing activity on monolayers of ciliated cells. We will also determine appropriate dosing and treatment regimes for reducing the cohesion of biofilms by standard biofilms screening assays and flow cells assays that better reproduce physiologic conditions. The reduced coherence of biofilms will also be combined with standard antibiotic treatments to understand the potentiating effects of PAAG on therapies used in CF patients. Upon completion of the project, the use of PAAG for further development will have proof of concept as a new and highly effective CF mucolytic treatment to address an unmet need in CF patient care.